1. Field of the Invention
The present invention relates to a rotational position detecting apparatus, or more in particular to a capacitive rotational position detecting apparatus capable of detecting the rotational position of the crank shaft of the automobile or the like without delay regardless of the rotational speed of the rotating member such as the crank shaft.
The U.S. patent application Ser. No. 105,118 filed Dec. 19, 1979 now abandoned and the U.S. patent application Ser. No. 159,855 filed June 16, 1980 now U.S. Pat. No. 4,350,981 by the same applicant are copending applications with the present application.
2. Description of the Prior Art
In a conventional apparatus for detecting the rotational position of the crank shaft or the like of, say, an automobile, a member of a magnetic material wound with a coil is placed opposite to the rotating member so that an alternating electromotive force is induced in the coil by the change of magnetic fluxes caused by the unevenness or projections of the rotating member thereby to detect the rotational position of the rotating member.
The apparatus of this type has the disadvantage that the alternating electromotive force induced in the coil is affected by the change of magnetic fluxes causing the electromotive force, namely, the rotational speed of the rotating member and therefore at low rotational speeds of the rotating member, substantially no alternating electromotive force is generated, thus making it impossible to detect the rotational position of the rotating member.